Dyson v7 Trigger cordless vacuum - TEARDOWN of battery pack

[ruddlescounty]

Slightly related, sorry! with all the experience on here - does anyone know what the 10 red flashing light sequence means on the dyson SV03? i have balanced a battery previously refusing to charge; all looking good (reporting 1700mah capacity) but when i put it into the vacuum i get the 10x red. the batt still has its cover off and balancing cables soldered on - but i cant see any "body" switches inside to check for this.
so, just asking in case anyone knows...

[rulof]

apparently, a strong voltage drop during start-up. 10 red is an error in the charging process. if you replace the batteries should work fine.

[ruddlescounty]

thanks for the reply.
got a few of these dyson batteries.
Is there anywhere i can see a list of codes and meanings?
latest one is 10x BLUE flashes. this is after i have rewritten eeprom from a 32x red flash battery.
several balanced charge/discharge cycles later - all indicating approx 1550mAh capacity, i now get the 10xBlue when i press the battery button.
any ideas?

thx

[rulof]

thanks for the reply.
got a few of these dyson batteries.
Is there anywhere i can see a list of codes and meanings?
latest one is 10x BLUE flashes. this is after i have rewritten eeprom from a 32x red flash battery.
several balanced charge/discharge cycles later - all indicating approx 1550mAh capacity, i now get the 10xBlue when i press the battery button.
any ideas?

thx

it's clear without ideas here.
it is necessary to replace the batteries.

[tinfever]

thanks for the reply.
got a few of these dyson batteries.
Is there anywhere i can see a list of codes and meanings?
latest one is 10x BLUE flashes. this is after i have rewritten eeprom from a 32x red flash battery.
several balanced charge/discharge cycles later - all indicating approx 1550mAh capacity, i now get the 10xBlue when i press the battery button.
any ideas?

thx

it's clear without ideas here.
it is necessary to replace the batteries.

I'm not sure you necessarily need to replace the cells. I'm not sure there is any good info out there on what the stock firmware LED codes mean, specifically. I'd check the Dyson manual for any clues and Google around but if you can't find any info on that blink code, it's possible no one knows. You could flash my custom firmware (FU-DYSON-BMS) to get more specific LED codes if you wanted. Also, make sure it isn't something simple like the battery needing to be plugged in due to a fully_discharged flag being set or something, or the battery turning itself off because it isn't seeing a large enough load. Other than that, it's possible your cell capacity is okay but the ESR is too high so as soon as you try to use it with a high current load like the vacuum, the cell voltage drops and it goes in to low voltage cutoff.

[rulof]

thanks for the reply.
got a few of these dyson batteries.
Is there anywhere i can see a list of codes and meanings?
latest one is 10x BLUE flashes. this is after i have rewritten eeprom from a 32x red flash battery.
several balanced charge/discharge cycles later - all indicating approx 1550mAh capacity, i now get the 10xBlue when i press the battery button.
any ideas?

thx

it's clear without ideas here.
it is necessary to replace the batteries.

I'm not sure you necessarily need to replace the cells. I'm not sure there is any good info out there on what the stock firmware LED codes mean, specifically. I'd check the Dyson manual for any clues and Google around but if you can't find any info on that blink code, it's possible no one knows. You could flash my custom firmware (FU-DYSON-BMS) to get more specific LED codes if you wanted. Also, make sure it isn't something simple like the battery needing to be plugged in due to a fully_discharged flag being set or something, or the battery turning itself off because it isn't seeing a large enough load. Other than that, it's possible your cell capacity is okay but the ESR is too high so as soon as you try to use it with a high current load like the vacuum, the cell voltage drops and it goes in to low voltage cutoff.

I've tried it many times already. even with a capacity of 1800-1900 milliamps, the batteries do not pull like that. on your firmware, most likely there will be error 16.

[tinfever]

I've uploaded Google Translate images of rulof's photos for anyone else.

I've tried it many times already. even with a capacity of 1800-1900 milliamps, the batteries do not pull like that. on your firmware, most likely there will be error 16.

Would you be able to share that entire document you took a picture of? It looks very useful.

Also, would you be able to measure the VBACK pin of the ISL94208 with a scope when the error 16 occurs on trigger pull on a bad battery? I'm curious if VBACK is dipping below 2V, and if it is dropping that low, I'm curious if adding at 10uF capacitor to the VBACK pin helps any.

My previous theory was that when the output is short circuited, the current wouldn't be enough to trip the short circuit protection but it would be enough to drop the battery cell voltage very low, causing the power to the VBACK pin to go too low, causing the ISL94208 to reset. In theory the same thing could happen with older battery cells with higher ESR when they aren't being short circuited but just subjected to inrush current demands. If my theory is correct, extra capacitance on the VBACK pin might let the ISL94208 ride though the inrush current voltage drop. This might also be why the ISL94208 reference design includes a 10uF cap there (which Dyson omitted).

[rulof]

Also, would you be able to measure the VBACK pin of the ISL94208 with a scope when the error 16 occurs on trigger pull on a bad battery? I'm curious if VBACK is dipping below 2V, and if it is dropping that low, I'm curious if adding at 10uF capacitor to the VBACK pin helps any.


currently out of stock with error 16. as soon as it appears, I will take measurements.

[bluesight]

In case anyone is interested in an update on my progress. I found a really tricky hardware bug while working on the documentation, and it took me a couple days to figure it out and create a work around.

Current theory/procedure:
0) Directly short the output (or connect it to multiple electronic loads that appear as a short until they start to limit the current)
1) The trigger is pulled and output is enabled as usual
2) There is a massive current spike, but not so huge as to trip the short circuit protection (which has to be set to 175A because the next lowest step, 100A, is insufficient for vacuum startup).
3) The output is disabled, but probably not actually because short-circuit protection kicks in. It takes about 400us, vs the 190us for short circuit protection.
4) The ISL94208 RESETS ITSELF AND DOES NOT PROVIDE ANY ERROR FLAG. Thus it is not obvious what happened.
     - This is likely because during a hard short, there can be a current spike of 140A+.
     - This causes the voltage on VBACK (attached to cell 1) to drop as low as 1.46V (vs 3-4.2V normally).
     - VCC for the ISL94208, which is connected to Cell 6 drops as low as 10.5V but that's still above the POR voltage
     - This is below the listed typical POR voltage (no minimum provided) for VBACK and is likely causing the reset of the ISL, which wipes all registers.
     - All of this is likely caused because Dyson omitted the 10uF capacitor for VBACK shown in the ISL94208 datasheet (page 32).
5) The normal I2C commands to the ISL fail while it is resetting, causing I2C errors.
6) Previously, I2C errors were handled by resetting the PIC. So the PIC is reset.
7) The PIC starts up and sees the trigger is pulled and the ISL is presenting no error flags.
8 ) Wash, rinse, repeat. Go to step 1.

I've determined I can set some of the User Flag bits and periodically check those to determine of the ISL has silently reset itself. If those bits are cleared, it then asserts an ISL_BROWN_OUT error, rather than having the output flap. These User Flag bits also have to be checked in more than one place in the main loop because the ISL doesn't reset *immediately* after the output enable bit is set on a dead short, so if I check the User Flags immediately afterwards they'll still be fine. I also had to add more elaborate I2C error handling than just resetting the PIC since that would prevent the ability to detect that the ISL reset.

I also tried to assess how the stock batteries react to this fault. I blew the MOSFET and the fuse. Then I replaced the MOSFET and shorted out the fuse. Then the MOSFET blew up again (that could be due to my bad soldering though). At this point I decided I needed to not permanently destroy my last working V6 BMS board since I still need to test that my firmware is compatible with it. Most development was done with a V7 BMS board but it was designed to be compatible with V6 boards too. There are a few different versions of the V6 BMS board, so after I publish everything it would be helpful for anyone willing to test the firmware on a previously untested board version are report their results.

When I want to quit the program, it won't let me, and I get this message: System.UnauthorizedAccessException: Access to the path 'C:\Program Files (x86)\Microchip\PICkit 3 v3\PICkit3.ini' is denied.
The ZIP contains 3 other ZIPs, do I have to invoke those other files too in some way?
An I'm running Win7-64b.

Edit, it's running now, but still can't select the 16LF1847
Edit 2, can select it now, but still get the error while trying to quit.

I think that error when trying to close the PICKit 3 programmer program is "normal". I always get it too. You can thank Microchip for that.

I think I have this problem. I did your firmware update. Unfortunately, I may have done a short when fiddling the switch near the exposed posts. Firmware update successful with all blink/color codes working. Charge codes working. When in vacuum and pulling the trigger, I get the 16 red blink "brownout" code. Tested vacuum motor with external supply and it works. Did attach VDD at PIC program time. So multiple opportunities to glitch the ISL94208. If that's the problem, this post seems to indicate that the ISL can be reset (or not). I see in your code that you provide a reset segment...?

void ISL_Init(void){
    ISL_SetSpecificBits((uint8_t[]){WriteEnable, 5, 3}, 0b111);    //Set all three feature set, charge set, and discharge set write bits
    ISL_SetSpecificBits(ISL.FORCE_POR, 1);                          //Make sure the ISL is clean reset

So, is this the problem, and is it permanent or fixable?
Tnx!

[tinfever]

I think I have this problem. I did your firmware update. Unfortunately, I may have done a short when fiddling the switch near the exposed posts. Firmware update successful with all blink/color codes working. Charge codes working. When in vacuum and pulling the trigger, I get the 16 red blink "brownout" code. Tested vacuum motor with external supply and it works. Did attach VDD at PIC program time. So multiple opportunities to glitch the ISL94208. If that's the problem, this post seems to indicate that the ISL can be reset (or not). I see in your code that you provide a reset segment...?

void ISL_Init(void){
    ISL_SetSpecificBits((uint8_t[]){WriteEnable, 5, 3}, 0b111);    //Set all three feature set, charge set, and discharge set write bits
    ISL_SetSpecificBits(ISL.FORCE_POR, 1);                          //Make sure the ISL is clean reset

So, is this the problem, and is it permanent or fixable?
Tnx!

For future reference, the dedicated forum thread would be the best place for questions like this: https://www.eevblog.com/forum/projects/fu-dyson-bms-an-(unofficial)-firmware-upgrade-for-dyson-v6v7-vacuum-bms/

If the battery is able to charge properly, I think the ISL94208 is working okay. I don't recall precisely what checks I run using the ISL94208 but I suspect at least one of them would fail if it wasn't operating. The PIC wouldn't run at all without the 3.3V from the ISL, and the ISL handles the multiplexing of all of the battery cell voltages so unless it got stuck reporting an identical valid result for every cell, the cell voltage checks wouldn't pass at all. Also, I just looked at the code again, the only way charging would work properly is if the ISL brown out check function passed, which would only work if the ISL is responding to I2C commands properly.

Please also check if the battery LEDs act normally if you press the button with the battery out of the vacuum with no load attached.

If that works fine, I suspect your battery cells have too high of an ESR and the load of the vacuum might be causing the cell voltage to drop enough to brown out the ISL. This is what rulof and I were discussing. I don't know what equipment you have but you could try to measure the battery ESR either with a battery tester, or by applying a known load and measuring the voltage drop. You could also try to measure the voltage drop on the VBACK pin of the ISL94208 during vacuum startup with an oscilloscope and see how far that voltage is dropping.

My current theory is that it is the inrush current of the vacuum triggering these errors on batteries with high cell ESR, but at least some batteries might be able to sustain the normal running current if we could ride through the inrush-caused-voltage-drop.

[PavChu]

Hello everyone, thank you for participating in this forum, especially the author of the custom firmware (FU-DYSON-BMS) and his colleagues and inspirers. This allows many people to solve their problems with batteries, as well as reduce the number of used batteries in the trash.
I want to ask the guys. Can PICkit 3.0 (when properly connected according to thewiring diagram) automatically not detect PIC16LF1847 on the 61462 PCB and the 188002 PCB. There are two non-working ones. The EEPROM is also not displayed in both cases. When the voltage is applied via PICkit 3.0 to a PCB that is not connected to the power elements, the indicator light reacts and changes color when the voltage changes from 2.5 to 5.0 V. When connecting the PCB to the elements, the LED indicator does not react in any way. I thought maybe the PIC16FLF1847 is just disabled somehow, maybe with MPLABX? In any case, Dzyakuyu syabry!

[tinfever]

Hello everyone, thank you for participating in this forum, especially the author of the custom firmware (FU-DYSON-BMS) and his colleagues and inspirers. This allows many people to solve their problems with batteries, as well as reduce the number of used batteries in the trash.
I want to ask the guys. Can PICkit 3.0 (when properly connected according to thewiring diagram) automatically not detect PIC16LF1847 on the 61462 PCB and the 188002 PCB. There are two non-working ones. The EEPROM is also not displayed in both cases. When the voltage is applied via PICkit 3.0 to a PCB that is not connected to the power elements, the indicator light reacts and changes color when the voltage changes from 2.5 to 5.0 V. When connecting the PCB to the elements, the LED indicator does not react in any way. I thought maybe the PIC16FLF1847 is just disabled somehow, maybe with MPLABX? In any case, Dzyakuyu syabry!

The latest recommendation is to not power the board with the PICKit and to leave the VCC wire disconnected. The battery should be able to power itself by pressing the button and applying a magnet to the reed switch if applicable. The PIC is a 3.3V version so you definitely shouldn't supply 5V. Any working board should be auto detected by the PICKit software I believe.

[PavChu]

I got you, Tinfever! Thank you sincerely 

[rulof]

I have two dyson v10- sv17 batteries.
one is fully functional,
the other is blocked.
the atasamd20e15 processor is installed.
there is a programmer j link v9.
when connected, he wants to erase the firmware.
tell me is it possible to read and flash only eeprom?
by analogy with dyson v7-v8?

[deuteron]

Dear Alll,
first of all many many thanks to all, who have contributed to this extremely interesting thread ! The work of tinfever & co is absolutely marvelous ! I read the thread from the very beginning since I'm a 'proud' owner of a Dyson V8 (SV10). The device was sold with a working battery, but the preowner said it is running only about 20 min with the actual battery. After having learned so much about the interior of the dyson batteries, I was curious to examine mine in more detail too. I'm not planning to 'repair' the pack or to change the cells, it's just that I wanted to now what's wrong. So I drilled alltogether 12 holes in the two side walls of the casing to be able to measure the individual cell voltages. Against my suspicion the pack is balanced pretty well, showing voltage between 4.07 and 4.12 V with an average of 4.10 V  in the completely charged state, i.e. the charger stopped charging, all LEDs off. After all investigations done by various people about this batteries this behaviour was unexpected, at least to me. My imagination was so far that the charger charges the cells until the highest of them reaches 4.2 V, the unsual maximum voltage of Li ion cells. Ok, it's not much of a capacity which is unused in my case (got 24.5 instead of 25.2 V max). Nevertheless it looks like the charger doesn't use the full cell capacities. What do you think, could this be a fault from factoty, some bad adjustment of the parameters or even a 'feature' to sell faster and more batteries ?
What's your opinion ? Did you see such an behaviour in your battery packs too ?
Best regards
Stefan